Telephone-repeater.



s. .L. AMPBELL; TELEPHONE RBPEATER. I APPLIOATION FILED 001229, 1908.RENEWED HA3. 3, 1010.

Patented Nov. 15, 3919.

2 SKEBTFEZHEET l.

UNITED strn'rns PATENT OFFICE.

smart L. QAMPBELL, or PRAIRIE. cm, oaneon.

'rnnnrnonn-anrnarnn Application filed October 29, 1908, Serial No.460,108. awed March a, 1910. Serial No. 547,125;

State ofOregon, have invented a new and useful Telephone-Repeater, ofwhich the following is a specification. I

This invention has reference to improve- 'ments in telephonic repeatersand is designed to provide a means whereby the range of telephonictransmission may be Y lar ely. increased;

n accordance with the present inuention,

the transmitting, stationis provided with the ordinary microphonicflunit and local circuit and by this means electrical impulses corresonding to sound waves aretrans-. to aline. At the distant end of themitte line is a receiver element, to the armature of which is attached amicrophonic element in a local microphonic circuit, which in turn is inoperative relation, inductively, to another transmitting line leading tothe dis: tant receiving point, ,where there is located a telephonicreceiver. The distant receiving point is also transmitter in u'ctivelyrelated to another transmission line; leading to the originaltransmitting station, where there is also located a telephonic receiver.The system thus includes a complete. transmitting circuit and a completereceiving circuit at each station and at intermediate points thesecircuits include a telephonic repeater. If

the line be exoessively'long, then a number.

of 'repeaters'may be included one after the other at proper intervals inthe line.

'The invention will be best understood from a consideration of thefollowing detail description. taken in connection with the accompanyingdrawings forming a part of this specification, in which drawings,

Figure 1 is a diagrammatic representation of a complete transmitting andreceiving circuit connecting two distant stations, and including in eachcircuit a telephonic repeater. Fig. 2 is'a central section throu h therepeater element or unit embodying t e invention. Fig.3 is asimilarsection at right angles to that of Fig. 2'.

Referring to the drawing there is shown at 'one station, which forconvenience will;

rovided with a telephonic Lby the reference numeral 2. The transmitter 1is iu a local transmitter circuit 3 electrical energy, and a telephonicinduction coil 5, the primary winding of which is in the circuit 3. Thesecondary winding of the coil 5 is in the line circuit 6, one branch 7of which, leads to a common return conductor 8, if the system be an allmetal system, or this conductor 8 may lead to ground. The otherbranch 9of the circuit 6 includes the winding 10 of a telephonic receiverll, andthis conductor 9 also leads to the common return 8 or to the ground asthe case may be.

In operative relation to the receiver-magnet 11 is an ironarmature 12controllin a micro honic element 13 of any suita le type, butparticularly of a delicate type, re-

12. The microphonic. element is in a local circuit 14 including abattery15 or other source of electric current, and the primary winding of atelephone induction coil 16. The secondary windingof the coil 16 is in aline circuit 17, one member 18 of which is connected to the commonreturn 8 or is grounded as the casemay be, and the other member 19 ofwhich includes a. telephonic receiver 20.

For convenience of description, the receiver 20 will be assumed to be atthe receivin the drawings by the letter B. At station cluded in a localmicrophone circuit 22 which circuit is supplied with current fromasuitable .source of electric energy such as the battery 23, and alsoincludes the primary -winding of a telephone induction coil 24.

a line circuit 25, one side 26 of which,is connected to the commonreturn 8 or to ground and the other side 27 ofwhich is ground andincludes the coil 28 of a telephonic receiver 29. In ppe'rative relationto the active ends of the receiver magnet isan armature 30 controlling amicr'ophonicelv meat 31 in a local microphone circuit 32.15;: which isincluded a battery 33 or other winding of a telephone induction coil 34.The secondary winding of the coil 34 is in another line circuit 35, oneside of which 1ssponsive to weak vibrations of the armature alsoconnected to the common return 8 or source of electric current, and theprimary- Specification of Letters Patent. Pat ented Ngw, 15 1910including a battery 4 or other source of ing station, and this stationis designated B there is a' microphonic transmitter 21in- The secondarywinding of the coil 24 is in connected to the common return 8 or tothe Iground as the case may be, and the other side 37 of which is alsoconnected to the common return or ground andinchides the receiver 2before referred to at the station A.

The two stations A and B are thereby coupled together by two distinctcircuits in each of which is a microphonic transmitter at one endand atelephonic receiver at the other end, and each of'tliese circuitsincludes a relay or repeater operative to telephonic currents. Let it besupposed that the dis tance'between the Stations A and B is so greatthat telephonic communication-is practically impossible because of theivcalnqiing of the current over such long transmission lines. Let italso be assumed that the repeater circuit 14 or 32 is at an intermediatepoint between the two stations A and B. The distance'from station A tothe repeater circuit 14, or from the station B to the re' peater circuit32 is such that the receiver 11 or 29 as the case may, be is stillvigorously actuated by the telephonic current coming from the respectivestations. The currents actuating the receiver 11 or 29 as the case maybe 'will cause fluctuations of the currents in the circuits 14 or 32,through the microphonic element 13 or 31, and since the batteries 15 or33 furnish new or additional energy in the circuit 14 or 32respectively, greatly strengthened telephonic currents are thrown uponthe receiver circuit. 17 and 3.3.

and the result is that the receivers 20 or 2 as the case may be arestrongly actuated and telephonic messages "WlllCl'l would beimperceptible or' heard with ditliculty over the distance between thestations 'A and B are heard at the receivers 2 and 20 strongly anddistinctly. It will be understood of course, that ifthedistance betweehthe stations A and B 'be too great for proper transmission with a singlerepeater then additional repeater circuits may be interspersed betweenthese stations. The arinatui'es 12 and 30 areof such thickness as toprevent any distortion or buckling of the metal, but move as a wholeunder the impulses of the receiver magnets, thus communicating all themovement to thefinicrophonic element. The armature isnot connected toany part of the mechanism other than the carbon box or variableresistance medium.

In Fi 's2and 3 there-is shown a practical form of telephone repeaters,In these figures the coils 10 are shown as of the type usually employedin connection with telephone receivers, and these coils'are providedwith'soft iron pole'l pieces 88, connected to the polar end or apermanent magnet 39 by means of a screw bolt 40 of non-magneticmaterial, the pole pieces being held apart and in magnetic engagementwith the polar ends of the magnets 39 by a. spacing of non-magneticmaterial. 'Betwesn the magnet 39 and the coils 10 the pole pieces wanespass through slots in the base of a cup 42, designed to inclose andprotect the. coils l0 and between the inner face of the base of the cupand the coils there is a dished supporting disk '3, resting on anotherdisk 44 of some soft non-resonant material, such for instance as felt.Made fast to the ends of the blocks 41 remote from the coils 10,

this conducting strip also lies along the block 4l, from which, if thelatter be of metal, the strip is insulated by a layer 49 of insulatingmaterial. The strip 48 is further held to the block 41 by a screw 50,which, when the block ,41 is of metal, is insulated from said strip. Thestrips 48 liebetween the legsot the magnet 39 and, the ends thereofremote from. the 'binding posts 46 are connected by conductors 51 to therespective ends of the coils 10, thiase'canductors being suitablyinsulated where necessary. The cup 42 is formed at its open end with anannular flange or ledge 52, over-- riding the free edge of an inwardlydirected I annular flange on a ring 54. Extending diametrically acrossthe ring 54 'is a bridge 55,

secured at each end to the ring and between this bridge piece and theledge 52 of the cup 42 are spacing blocks 56, serving when the bridge55' is in place, to firmly clamp the ledge 52 of the cup 42 against thetlange 53 of the ring The central portion of the bridge 55 is formedwith a boss 57 receivimc, the stem 58 of the microphonic element 13 or31, as the case may be.

The inicioplionic element is not shown in the "drawings in detail, sinceits structure be similar to that u'sually'eniployed in connect on with ncrophonic transmitters, but it s powerful and delicate a type as po .0.The movable member of the Dll('i nic elenient cai'ries thedim. phi'agni12 or 30, as the case iiia be, and this-diaphragm is made of a small butrigid piece of metal, only large enough to bridge 1.

erme'ee The cup 42 and the ring 54, as clamped together by the ring 55and spacing blocks 56, form a rigid support for the coils 10 or 28, asthe case may be, and the microphonic element may be very delicatelyadjusted into operative relations With the said coils and be ultimatelyclamped into position by aset screw 60 iiitlie boss 5'? and a clamp nut61. In order to inclose the working parts of the repeater there heprovided e cap 62, indicated in dotted lines in Figs. 2 and 3, and thiscap is applied to the ring 54:. The cup 42-, together with the heavyring 54 rind hridge'piece 55, forms a very rigid support for veryaccurately mainteinihg the receiver coils and the microphonic element inrelative position one to the other during the operation ofthe structure.

hat is claimed is:

y l. A telephone repeater system comprising a local microphone circuitat one station, e line circuit in inductive relation to the mi crophonecircuit, a repeater unit at a distent point in said circuit comprisingreceiver coils and a magnet, an inclosing cup carried thereby, a flangedring receiving and engeged by the cup, a hri ge piece on the ring andclamping the cup to the ring, a microphonic element carried by thebridge piece, a free armature carried by the microphonic element inoperative relation to the free ends of the receiver magnet pole pieces,a circuit controlled by the last named microphonic element, and acircuit in inductive relation tov the last named circuit and containingreceiver.

2.v A telephone repeater unitcomprising receiver coils and a magnet, eninciosing cup carried thereby, a flanged rim receiving and engaged bythe cup, at bri igc piece on the ring and clamping the cup to the ring,a microphonicielement carried by the bridge piece, and at free armaturecarried by the microphonic element in ope 'etive relation to the freeends of the receiver megnet pole pieces. v

In testimony that I claim the foregoing as my own, I have hereto efixedmy signature in the presence of two witnesses.

SAMUEL L. CAMPBELL.

